EMBRYOLOGY-1

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Questions and Answers

What happens to oogonia from birth to puberty in females?

They double in number each year.

They decrease from 7 million to 2 million.

They decrease from 2 million to 40,000. (correct)

They remain constant at 400 throughout this period.

What transformation do Sertoli cells perform on testosterone?

Convert it into estrogens (correct)

Store it as cholesterol

Turn it into DHT

Release it as free testosterone

In males, when do spermatogonia become dormant?

Until the age of 6 weeks. (correct)

After the first meiotic division.

Immediately after fertilization.

At birth until puberty.

What hormone does inhibin inhibit the secretion of?

Follicle-stimulating hormone (FSH) (D) Signup and view all the answers

Which of the following is a cause of male infertility?

Abnormal spermatozoa (C) Signup and view all the answers

Which statement about meiosis in females is true?

Meiosis I is completed at ovulation. (D) Signup and view all the answers

What is the result of one spermatogonium during spermatogenesis?

It gives rise to four spermatozoa. (A) Signup and view all the answers

Which type of ovarian follicle contains oocytes that have initiated meiosis I?

Primordial follicles (D) Signup and view all the answers

What characterizes the process of gametogenesis in females compared to males?

It has a synchronous and slower pace. (D) Signup and view all the answers

How do follicular cells communicate with the oocyte?

Via the zona pellucida (D) Signup and view all the answers

What percentage of involuntary childless couples are detectable for male infertility?

30-50% (C) Signup and view all the answers

How many functional oocytes does one oogonia produce throughout development?

One. (A) Signup and view all the answers

Which hormone initiates meiosis I in males?

Testosterone. (D) Signup and view all the answers

Which type of follicle develops from primordial follicles?

Primary and secondary follicles (B) Signup and view all the answers

What is a common misconception regarding the effects of medications on male fertility?

Some medications can lead to oligospermia (A) Signup and view all the answers

What happens to the number of primary oocytes from the 5th month of pregnancy until birth?

They decrease to 2 million. (B) Signup and view all the answers

What is the primary purpose of measuring Crown Rump Length (CRL) in the first trimester?

To determine gestational age (A) Signup and view all the answers

Which period is characterized by the greatest risk for teratogenic effects on fetal development?

Weeks 3-8 (B) Signup and view all the answers

What is an example of a teratogen?

A pharmaceutical drug (C) Signup and view all the answers

What is the main focus of the embryonic period from weeks 3-8?

Morphogenesis of all organs (C) Signup and view all the answers

What percentage of birth defects have an unknown cause?

50%-60% (C) Signup and view all the answers

Which of the following best describes the concept of multifactorial inheritance?

Both genetic and environmental factors play a role in defects (A) Signup and view all the answers

What critical phase follows fertilization in human embryology?

Cleavage (C) Signup and view all the answers

Which gene mutation is associated with Hutchinson-Gilford progeria syndrome?

LMNA (B) Signup and view all the answers

Which structure in the male genital tract is responsible for the maturation of sperm?

Epididymis (B) Signup and view all the answers

During what embryological process are the foundational tissues for all organs formed?

Gastrulation (C) Signup and view all the answers

What role does the blood-testis barrier play in male fertility?

It prevents exposure of antigens to circulating blood. (B) Signup and view all the answers

During spermatogenesis, which of the following best describes the transition from Type A to Type B spermatogonia?

Type B spermatogonia arise from Type A through mitotic division. (B) Signup and view all the answers

What occurs during the cytoplasmic events of spermiogenesis?

Excess cytoplasm is eliminated to reduce sperm weight. (B) Signup and view all the answers

Which statement accurately describes the formation of the acrosome during sperm development?

It is produced at the apical end of the nucleus from the Golgi apparatus. (C) Signup and view all the answers

What is the primary outcome of meiosis II in spermatogenesis?

Development of secondary spermatocytes into spermatozoa. (D) Signup and view all the answers

What significant change occurs to histones during the nuclear events of spermiogenesis?

Histones are replaced by protamines to facilitate DNA compaction. (A) Signup and view all the answers

What consequence of trauma to the blood-testis barrier can lead to infertility?

Access of circulating antibodies to developing germ cells. (A) Signup and view all the answers

What is the duration of the entire spermiogenesis process?

24 days. (D) Signup and view all the answers

What role do fimbriae play during ovulation?

They capture the ovulated complex as it slips out of the ovary. (C) Signup and view all the answers

During which phase does the ovulated complex move rapidly to the uterus?

Rapid phase from the isthmus to the uterus lasting 8 hours. (C) Signup and view all the answers

What is a major cause of infertility related to the uterine tube?

Blockage due to infections or endometriosis. (B) Signup and view all the answers

What is the average pH range of seminal fluid?

7.2 - 7.8 (B) Signup and view all the answers

How long can spermatozoa retain their function in the female reproductive tract?

80 hours (A) Signup and view all the answers

What components of seminal fluid aid in the energy supply for spermatozoa?

Fructose from seminal vesicle secretions. (D) Signup and view all the answers

What is the normal volume of ejaculate during human ejaculation?

2-6 ml (D) Signup and view all the answers

Which type of muscle aids in the movement of the ovulated complex through the uterine tube?

Smooth muscle (C) Signup and view all the answers

What is the primary function of the theca interna in the ovarian follicles?

To produce estrogen precursors and contain LH receptors (D) Signup and view all the answers

What is the significance of the antrum in antral follicles?

It is rich in hyaluronic acid and proteins, facilitating follicle growth (C) Signup and view all the answers

During the transition from pre-antral to antral follicles, what occurs among the granulosa cells?

Formation of larger intracellular spaces filled with fluid (B) Signup and view all the answers

What is the primary source of testosterone in the ovarian follicle?

Theca interna (B) Signup and view all the answers

Which hormone triggers the production of estrogens during follicular development?

Follicle-stimulating hormone (FSH) (B) Signup and view all the answers

What role do Cell-Exner bodies play in pre-antral follicles?

They are spaces filled with fluid that assist in the follicle's maturation (C) Signup and view all the answers

What occurs as a result of the increase in FSH and LH receptors in granulosa cells?

Enhanced hormone synthesis and follicular development (C) Signup and view all the answers

What is the fate of most growing follicles during their development?

They undergo apoptosis and degenerate (A) Signup and view all the answers

Study Notes

Periods of the Human Body

Trimesters are used medically, with the first, second, and third trimesters defining stages of pregnancy.
The first trimester is defined embryologically as the period from fertilization to implantation in the uterus, encompassing the zygote, morula, and blastocyst stages.
The embryo phase spans from implantation to the eighth week, and the fetal phase is from the eighth week onward.
Development continues after birth, with the lungs, for example, not fully developing until the seventh year.

Dating Pregnancy

Fertilization age is calculated from the moment of fertilization, though this moment is often not precisely known.
Menstrual age is reckoned from the onset of the woman's last menstrual period (LMP), commonly considered a 28-day cycle.
A standard pregnancy lasts approximately 40 weeks, though some are slightly shorter or longer (38 weeks is another commonly cited fertilization age, with an average range between 38 and 40 weeks for menstrual age.

Estimated Due Date (EDD)

Accurately determining the EDD is difficult using only the LMP, as it assumes a consistent 28-day cycle.
Crown Rump Length (CRL) measurement taken via ultrasound in the first trimester is more accurate for calculating the EDD.

Teratogens

Teratogens are chemical, physical, or biological agents that can affect fetal development.
Vulnerability is greatest during the embryonic period (3-8 weeks) as this is when organs form.

Causes of Birth Defects

Genetic factors such as chromosomal abnormalities or gene mutations can lead to birth defects.
Environmental factors like drugs, alcohol, viruses, radiation, and chemicals can contribute.
Multifactorial inheritance occurs when both genetic and environmental factors play a role.
About 50-60% of birth defects have unknown causes.

Phases of Human Embryology

Gametogenesis is the formation of gametes (sperm and egg).
Fertilization unites the gametes.
Cleavage involves cell division.
Gastrulation establishes the body plan.
Morphogenesis sculpts the body plan.
Organogenesis forms organs and tissues.

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Description

Test your knowledge on the process of gametogenesis in both males and females. This quiz covers important concepts such as the transformation of cells, hormonal regulation, and statistics related to infertility. Perfect for students studying reproductive biology or related fields.